An Apple a day keeps the doctor away, unless that doctor is now gathering your health data through your Apple iPhone.

Apple is embarking on its boldest push yet into health, with a new open source framework for letting medical researchers and software developers gather health data from iPhone owners and build health-related apps. Apple officially opened the framework, called ResearchKit, to all researchers and software developers on Tuesday, after announcing it at an event in March.

The idea behind ResearchKit is that, given the iPhone's prominence, it will allow for much more health data to be collected than through typical studies, helping researchers and clinicians to increase their understanding of diseases and health conditions. Researchers can tap into the framework to gather the data it has collected, while third-party app developers can build health-related apps on top of it.

More than 600,000 iPhone users have already enrolled in the first batch of research apps, developed using ResearchKit to study asthma, breast cancer, cardiovascular disease, diabetes and Parkinson's disease, Apple said on Tuesday.

By opening the framework to outside developers, Apple stands to usher in a wave of new apps aimed at letting people track their daily physical activity and health, while contributing the data to the larger scientific community.

Apps built on ResearchKit can access data from the iPhone's sensors like the accelerometer, gyroscope, microphone and GPS. With permission from the iPhone owner, ResearchKit apps can access data, like weight and glucose levels, from other health apps. ResearchKit includes customizable components that researchers can use to measure activities, create surveys and obtain consent from the user.

Privacy concerns are a big issue that could limit the use of ResearchKit and thus its effectiveness. Apple has said that iPhone owners will decide how their health data is shared, and that Apple will not see it. Still, participants are bound to have concerns over the security of their health data, and how it's handled by outside researchers.

Sage Bionetworks, a nonprofit biomedical research organization, has handled the collecting and storing of health data from several of the apps already developed with ResearchKit. Sage has said that it strips out information like people's names and date of birth, encrypts the health data and stores it on a secure cloud server.

Meanwhile, the U.S. Federal Trade Commission has reportedly met with Apple over the company's data policies, partly to ensure that Apple does not hand over health data to advertisers.

Apps for ResearchKit are available in Apple's App Store in the U.S., and will be coming to more countries in the future, Apple said. You need an iPhone 5, 5S, 6, 6 Plus or the latest generation iPod Touch to use ResearchKit apps.

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